2015 Audi S6

Think of the S6 as a boxer in a tuxedo. Outside, this A6 performance variant is all about classy understatement, and its interior is dressed to the nines in supple leather and fine wood. Underneath it all, however, is a 420-horsepower V8 that's ready to deliver a knockout punch at a moment's notice.

The big difference between the two, of course, is what lies under the hood. Whereas the A6 uses a supercharged six, the S6 packs a potent twin-turbocharged 4.0-liter V8 with 420 horsepower and 406 lb-ft of torque. That's enough to propel the sport sedan from zero-to-60 mph in the low four-second range.

The V8's partner in speed is a seven-speed dual-clutch automatic that serves up smooth but rapid shifts and can be controlled manually through steering wheel-mounted paddle shifters. Audi's quattro all-wheel-drive system helps the S6 conquer inclement weather and also improves handling by sending torque to the outside rear wheel to cut down on understeer in turns.

Despite its performance credentials, the S6 is no gas guzzler - it's rated at 17/27 mpg - due to a cylinder deactivation system that essential turns the engine into a V4 in low-throttle highway driving. Known as Cylinder on Demand, the setup employs active noise cancellation technology and active engine mounts to eliminate any NVH issues that would be uncouth in such a premium vehicle.

The S6 rides on a full air suspension with adaptive dampers, which can both be adjusted to suit the driver's preferences with a Drive Select system that also controls throttle response, steering effort and shift calibration.

Impressive Inner Sanctum
Aesthetes will find much to like in the cabin, which features organic lines rendered in rich soft-touch materials and set off by fine wood and metal trim. Supportive sports seats wrapped in cross-stitched leather, a three-sport multifunction steering wheel and a S-line instrument cluster are classy reminders of the S6's sporting intentions.

Being a modern Audi, the S6 is equipped with MMI, or multimedia interface, which includes an eight-inch pop-up display, a five-inch information LCD display and an optional heads-up display for the windshield. The MMI also boasts an industry first: the ability to recognize driver handwriting via the touch input pad, allowing for the input of both navigation and telephone information.

The S6 comes standard with Audi connect, which offers in-car WiFi along with real-time localized weather, news and live fuel prices. When equipped with an optional navigation system, the system includes Google Earth integration - complete with panoramic views and high-resolution 3D satellite and aerial imagery.

Standard and Optional Features
The S6 is fitted as standard with diamond-stitched leather upholstery, a navigation system with SiriusXM Traffic, a sunroof, heated and 12-way power-adjustable front seats, four-zone automatic climate control, a 14-speaker, 630-watt AM/FM/CD/SiriusXM/HD Radio Bose sound system, keyless start, adaptive xenon headlights with LED running lights, LED taillights, Bluetooth connectivity, a head-up display and 18-inch alloy wheels.

Occupant Safety
All S6 models are fitted with dual front, front knee, front side and full-length side curtain airbags. Rear side airbags are optional. Traction and stability control systems, electronic brakeforce distribution and a tire pressure monitoring system are also included as standard.

Optional safety features include active lane assist, which warns the driver when the S6 is wandering into an adjacent lane and can even gently steer the car back into the original lane. There's also Audi pre sense, which can detect obstacles in front of the S6 and apply the brakes to prevent a crash or mitigate its severity. Finally, Audi side assist alerts the driver when a vehicle is in one of the S6's rear blind spots.

Key Competitors
Like other Audi "S" models, the S6 is aimed at the gap between the base-engine and performance models of competing brands. As such, the Audi is aimed at the traditionally-styled, luxury-oriented Mercedes-Benz E550, the well-equipped Infiniti M56 and the BMW 550i, which offers enthusiasts the class-exclusive option of a true manual gearbox.